Vegetarians International Voice for Animals

Kidney disease

Kidney disease

The kidneys are two bean-shaped organs located in the lower back. Kidneys filter the blood to remove unwanted waste products broken down from our food and drink. They also remove excess liquid to help maintain correct fluid balance in the body.

There are many diseases and conditions that can affect the kidney function: kidney inflammation (glomerulonephritis); kidney infection (such as pyelonephritis); genetic disorders (such as polycystic kidney disease); hardening of the kidney due to a disease of the arteries (nephrosclerosis); kidney failure due to atherosclerosis (plaques forming in the arteries supplying the kidneys); autoimmune diseases (such as systemic lupus erythematosus); malaria; yellow fever; certain medicines; mechanical blockages (kidney stones) and physical injury.

Surveys have revealed that mild forms of kidney disease are surprisingly common among the general population. The global epidemic of type 2 diabetes has led to an alarming increase in the number of people with chronic kidney disease. Global estimates of people suffering with chronic kidney disease lie at over 50 million, of which one million experience kidney failure every year (Dirks et al., 2005). There may be no apparent symptoms, although small amounts of blood or protein may pass through the damaged filters in the kidneys into the urine. Such small amounts of blood and protein in the urine are not visible but can be detected by certain medical tests.

Normally protein is filtered out by the kidneys and no protein is excreted into the urine. However, when the kidneys are damaged, protein may pass into the urine. Other symptoms include retention of water in the body, called nephrotic syndrome. In some cases the damage to the kidney can be so severe that it leads to a build up of waste in the body and ultimately kidney failure. The symptoms of kidney failure include tiredness, sickness and vomiting.

Certain kidney disorders can lead to the formation of a kidney stone (renal calculi), a small hard mass in the kidney that forms from mineral deposits in the urine. Stones may form when there is a high level of calcium, oxalate or uric acid in the urine; a lack of citrate in the urine; or insufficient water in the kidneys to dissolve waste products.

Traditionally, a low-calcium diet has been recommended to reduce the strain on the kidneys in kidney stone patients. However, over time a low-calcium diet can cause problems in terms of bone health. In the last decade, attention has switched to the effects of animal protein on kidney stone formation. Several studies now suggest that a diet characterised by normal-calcium, low-animal protein and low-salt levels is more effective than the traditional low-calcium diet for the prevention of kidney stones in some people.

The relationship between an animal protein-rich diet and kidney stone formation was investigated by researchers at the Centre in Mineral Metabolism and Clinical Research at the Department of Internal Medicine in Dallas, Texas (Breslau, 1988). In this study, 15 young healthy participants were studied for three 12-day dietary periods during which their diet contained vegetable protein, vegetable and egg protein, or animal protein. While all three diets were constant with respect to sodium, potassium, calcium, phosphorus, magnesium and the total quantity of protein, they had progressively higher sulphur contents (due to the increased sulphur content of animal proteins compared to that of plant proteins). As the sulphur content of the diet increased, urinary calcium excretion increased from 103mg per day on the vegetarian diet to 150mg per day on the animal protein diet. The animal protein-rich diet was associated with the highest excretion of uric acid and therefore conferred an increased risk for uric acid stones (but not for calcium oxalate stones). The link between animal protein and kidney stone formation has since been demonstrated in both men (Curhan et al., 1993; Taylor et al., 2004) and women (Curhan et al., 1997).

Dr Neil Barnard, president of the PCRM, states that animal protein is the worst kind of enemy of people with a tendency towards kidney stones or any kidney disease (Barnard, 1998). The animal protein in red meat, poultry, fish, eggs and milk tend to overwork the kidneys causing their filtering abilities to decline. This may make matters worse in a person who already has kidney disease. Additionally, animal protein causes calcium to be leached from the bones and excreted in the urine, adding further to the burden on the overworked kidney.

A report published in the Lancet in 1992 suggested that soya products may be beneficial in kidney disease. Kidney disease patients with protein in the urine and high cholesterol levels were placed on a cholesterol-free, low-protein, low-fat, high-fibre vegetarian (vegan) diet containing soya products. The amount of protein excreted in the urine dropped considerably as did their blood cholesterol levels (D’Amico et al., 1992). It was uncertain whether these results reflected the reduction in dietary protein and fat or if the favourable results arose from a change in the nature of the food consumed. Either way, switching from a diet containing meat and dairy products to a plant-based diet containing less fat and protein and more fibre was beneficial to patients with kidney disease.

In addition to avoiding animal protein in the diet, increasing the potassium intake has been shown to yield benefits as potassium reduces calcium excretion, which can decrease the risk of stone formation. Additionally, the beneficial effect of increasing the fluid intake and the subsequent dilution of urine is well known (Curhan et al., 1993).

Lactose intolerance

Most people in the world are unable to consume cow’s milk and milk products after weaning because they are unable to digest the sugar in milk called lactose. This sugar only exists in mammals’ milk, including human breast milk. In order for lactose to be digested it must be broken down (to glucose and galactose) in the small intestine by the enzyme lactase. Most infants possess the enzyme lactase and can therefore digest lactose, but this ability is lost in many people after weaning, commonly after the age of two. This makes sense as no other mammal consumes milk after weaning. In the absence of lactase, lactose is fermented by bacteria in the large intestine, which leads to a build up of gas. Symptoms of lactose intolerance include nausea, cramps, bloating, wind and diarrhoea and usually appear within two hours of consuming food containing lactose. The symptoms of lactose intolerance and irritable bowel syndrome (IBS) are very similar, so misdiagnosis between the two conditions can occur.

Most infants are born with the ability to digest lactose but over time this ability decreases. There are other, more uncommon, causes of lactose intolerance including injury to the mucus membrane of the small intestine and digestive diseases of the small intestine such as ulcerative colitis and Crohn's disease.

Lactose intolerance varies widely between different ethnic groups: 
     95 per cent of Asian people 
     75 per cent of Afro-Caribbean people 
     50 per cent of Mediterranean people 
     10 per cent of  northern European people 
Source NHS Direct, 2005.

Lactose intolerance occurs in as few as just two per cent of some northern European populations and as many as 100 per cent of adult Asian populations (Swagerty et al., 2002). This widespread variation suggests that lactase deficiency is the normal or natural state and that the ability to digest lactose originates from a genetic mutation that provided a selective advantage to populations using dairy products (Swagerty et al., 2002). This idea is supported by William Durham in his book Coevolution (Durham, 1991). Durham describes milk as baby food not ‘intended’ for adult consumption. He describes how the ability to digest lactose is the exception to the norm and can originally be traced back to a minority of pastoral tribes: the Tutsi and Hutu of Rwanda; the Fulani of West Africa; the Sindhi of North India; the Tuareg of West Africa and some European tribes. People who have retained the normal intolerance of lactose include: Chinese, Japanese, Inuit, native Americans, Australian Aborigines, Iranians, Lebanese and many African tribes including the Zulus, Xhosas and Swazis. These people, generally, do not have a history of pastoralism.

In conclusion, drinking cow’s milk is neither normal nor natural. The health implications of being the only mammal to consume milk as adults (and not just that, milk from another species too) are becoming clearer in the scientific literature as levels of the so-called diseases of affluence soar.

The treatment for lactose intolerance is straightforward: avoid lactose. This means cutting out all dairy foods and checking labels for lactose in bread, chocolate and other processed foods.

Migraine

A migraine is much more than a bad headache; unless you suffer from them it is difficult to appreciate just how debilitating a migraine can be. Often people with a migraine can do nothing but lie quietly in a darkened room waiting for the pain to pass. The pain is excruciating, often accompanied by nausea, vomiting and an increased sensitivity to light and sound. A migraine can last for a few hours or a few days. Migraines occur more commonly in women than men and usually affect people in their teenage years up to around 40 years of age, although they do sometimes occur in children. It is estimated that almost six million people in the UK are affected by migraine.

A range of common factors that can cause migraines in some people have been identified. Foods are frequently identified as triggers and the most common culprits include dairy products (particularly cheese), chocolate, alcohol (particularly red wine), caffeine, citrus fruits, nuts, fried foods and foods containing monosodium glutamate (MSG) such as Chinese food, processed meats and frozen pizzas (NHS Direct, 2005). Other triggers include cigarette smoke, bright lights, hunger, certain drugs (such as sleeping tablets and the combined oral contraceptive pill), loud noises, strong smells, neck and back pain, stress and tiredness (NHS Direct, 2005). All these and others can lead to a migraine, and some people may experience a migraine following any one or a combination of these factors. 

The national medical charity Allergy UK lists cheese (particularly Stilton, Brie, Camembert and Emmenthal) as the third commonest cause of food-induced migraine after alcohol and chocolate. They suggest that 29 per cent of food-induced migraines are caused by alcohol, 19 per cent by chocolate, 18 per cent by cheese and 11 per cent by citrus foods. Other foods thought to trigger migraine include fried and fatty foods, onions, pork, pickled herring and yeast extract (Allergy UK, 2005).

In a study at Great Ormond Street Children’s Hospital in London, 88 children with severe and frequent migraines were treated with a diet that eliminated many foods linked to migraine, 93 per cent of the children responded well to the diet and were free of headaches (Egger et al., 1983). Foods were gradually reintroduced to identify those most likely to provoke a migraine. Top of the list was cow’s milk, followed by chocolate (containing cow’s milk), the food preservative benzoic acid, eggs, the synthetic yellow food colouring agent tartrazine, wheat, cheese, citrus, coffee and fish. Interestingly, children who had initially developed a migraine in response to factors other than food (for example flashing lights or exercise) no longer responded to these triggers while on the special elimination diet.

The relationship between food allergy or intolerance and migraine is difficult to prove and, despite the evidence, remains a controversial subject. However, the possibility of cow’s milk allergy or intolerance should be considered in all cases of migraine.

Multiple sclerosis and autoimmunity

Multiple sclerosis (MS) is the most common disease of the central nervous system (the brain and spinal cord) affecting young adults in the UK. MS currently affects around 85,000 people in the UK and twice as many women as men have MS. Although it usually occurs in young adults in their twenties and thirties, MS can occur in older people. It is rarely diagnosed in children and teenagers.

Sclerosis means scarring and multiple refers to the different sites at which the scarring can occur throughout the brain and spinal cord. In MS the protective sheath (myelin) that surrounds the nerve fibres of the central nervous system becomes damaged. When myelin is damaged (demyelination) the messages between the brain and other parts of the body become disrupted. Myelin protects the nerve fibres in much the same way that household electrical wires are protected by an insulating cover. If this cover becomes damaged the normal signalling route becomes disrupted and may result in a short-circuit. The severity of the symptoms depends on how much damage has occurred to the central nervous system. For some people there may be periods of relapse where there are few symptoms, then times when the symptoms become more severe including blurred vision, paralysis, slurred speech, lack of coordination and incontinence. 

The cause of MS is not yet fully understood but is thought to be an autoimmune disease whereby the body’s immune system attacks its own tissues. As with other autoimmune diseases, it is thought that a combination of genetic factors and environmental triggers cause the disease. Environmental triggers may include viruses, components of the diet or stress. Interestingly, the incidence of MS increases the further you get from the equator, whether going north or south. For example, MS is five times more common in temperate zones than in the tropics (NHS Direct, 2005). Campbell suggests that MS is over 100 times more prevalent in the far north than at the equator (Campbell and Campbell, 2005). In Australia the incidence of MS decreases seven-fold as you move towards the equator from the south to the north (Campbell and Campbell, 2005). This geographical distribution pattern applies to other autoimmune diseases including type 1 diabetes and rheumatoid arthritis (Campbell and Campbell, 2005).

Indeed, this phenomenon has been noted since 1922 (Davenport, 1922). Campbell suggests in his bookThe China Study that autoimmune diseases should be considered as a group rather than as individual diseases as they share similar clinical backgrounds and sometimes occur in the same person or among the same populations (Campbell and Campbell, 2005).

The research investigating the links between diet and MS date back over 50 years to Dr Roy Swank’s work first at the Montreal Neurological Institute in Norway, then at the Division of Neurology at the University of Oregon Medical School in the US. Swank was intrigued by the geographical distribution of MS and thought it may be due to dietary practices. Swank suspected animal foods high in saturated fats may be responsible as MS seemed to occur most among inland dairy-consuming populations and less among coastal fish-eating populations. Perhaps his best known trial was that published in the Lancet in 1990. In this study Swank followed 144 MS patients for a total of 34 years. Swank prescribed a low-saturated fat diet to all the participants but the degree of adherence to the diet varied widely. He observed how their conditions progressed. Results showed that for the group of patients who began the low-saturated fat diet during the earlier stages of MS, 95 per cent survived and remained physically active for approximately 30 years. In contrast, 80 per cent of the patients with early-stage MS who did not adhere to the diet died of MS (Swank and Dugan, 1990). It was concluded that saturated animal fats increase the risk of MS.

More recent studies have extended Swank’s findings and revealed a positive correlation between the consumption of cow’s milk and the incidence of MS. This later research suggests that there could be a combination of predisposing or precipitating factors involved in the aetiology of MS, and that environmental factors, such as the consumption of cow’s milk, play a part (Agranoff et al., 1974; Butcher, 1976). These and more recent studies suggest that cow’s milk may contain some component other than saturated fat that influences the incidence of MS. For example, it has been suggested that this factor or environmental trigger may be a virus (Malosse et al., 1992).

You are more likely to get MS if other people in your family have it (especially a brother or sister). This shows that there is an element of genetic predisposition in this disease. However, twin studies have shown that only about a quarter of identical twins with MS have a twin with the disease (Willer et al., 2003). In other words for every four genetically identical sets of twins (one of whom has MS) one other twin will have the disease and three will not. If genes were solely responsible for MS, the genes that cause MS in one twin would also cause it in the other. When considering the role of genetics in a disease, it is useful to look at what happens to the risk of that disease in migrating populations. As for cancer, heart disease and type 2 diabetes, people tend to acquire the MS risk of the population to which they move, especially if they move early in life. This shows that MS is more strongly related to environmental factors and diet than genes.

While the benefits of excluding milk from the diet may not have been directly proven for MS sufferers, there is evidence that a high intake of saturated fat increases the incidence of this disease. Others studies suggest that increasing the intake of unsaturated fatty acids (such as linoleic acid), vitamin D and antioxidants may be helpful (Schwartz et al., 2005). The overall message is clear: a plant-based diet low in fat, salt and sugar (and processed foods) and high in fresh fruits, vegetables, whole grains, pulses, nuts and seeds can provide all the nutrients required for good health and reduce some of the risk factors for MS or prevent making an already existing condition worse.

As the incidence of most autoimmune diseases correlates directly to the consumption of animal foods, this approach could help prevent other autoimmune conditions that occur increasingly among populations that consume high levels of dairy and meat products.

Overweight and obesity

Most people know what the term obesity means: an increased body weight caused by the excessive accumulation of fat. Overweight and obesity occur when more calories are taken into the body than are burnt up over time. In other words, if you don’t burn up the energy you consume it will be stored as fat, and over time this may lead to excessive weight gain and obesity. So someone who works in a very physically demanding job, such as a building-site labourer, may need between 4,000 and 5,000 calories per day to maintain their normal weight. Whereas an office worker who drives to work and does not take any exercise may only need 1,500 calories per day (NHS Direct, 2005).  

Another way of defining obesity is to measure your body mass index (BMI). This is your weight in kilograms divided by the square of your height in metres. There are many websites that can do conversions and calculations for you (see Appendix II). In England, people with a body mass index between 25 and 30 are categorised as overweight, and those with an index above 30 are categorised as obese. The Food Standards Agency’s BMI calculator describes 18.5 to 25 as healthy and suggests that a BMI of less than 18.5 is underweight (FSA, 2006). The average BMI of an adult in Africa and Asia falls between 22 and 23, whereas in North America and Europe the average BMI is much higher ranging from 25 to 27 (WHO, 2006d). In 2004 the FSA reported that the number of obese adults in the UK has risen considerably since the last survey in 1987; numbers of obese men have risen from eight per cent to 25 per cent and women from 12 per cent to 20 per cent (FSA, 2004). This survey showed that the level of obesity in men has risen faster than those of women. In addition, the FSA survey reported that 41 per cent of men and 33 per cent of women were found to be overweight.   

The main causes of obesity include an excessive intake of food coupled to a lack of exercise and a sedentary lifestyle. Other much less frequent causes include a genetic predisposition or an underlying illness (such as hypothyroidism). The British Medical Association (BMA) warns that childhood obesity levels have soared in the UK over recent years. In 2002 in the UK, 22 per cent of boys and 28 per cent of girls aged between two and 15 were either overweight or obese (BMA, 2005). The BMA attribute this rise to the fact that children are eating too much for the amount of physical activity they undertake. This is very worrying as early childhood obesity tends to indicate adult obesity which can lead to serious health risks later in life. Obesity is a known risk factor for many illnesses including type 2 diabetes, heart disease, hypertension, stroke, gall bladder disease and certain forms of cancer especially the hormonally related and large-bowel cancers.

The WHO suggests that as the degree of affluence increases, diets high in complex carbohydrates give way to diets high in saturated fats and sugars (WHO, 2006d). This combined with a shift towards less physically demanding work, an increasing use of automated transport, technology in the home and more passive leisure pursuits means that we are less active than our parents and our grandparents.

The WHO suggests several ways to lose weight including eating more fruit, vegetables, nuts and whole grains; engaging in daily moderate physical activity for at least 30 minutes; cutting the amount of fatty, sugary foods in the diet and moving from saturated animal-based fats to unsaturated vegetable-oil based fats (WHO, 2006d). Whole milk, cheese, cream, butter, ice-cream and most other dairy products, apart from skimmed and non-fat products, contain significant amounts of saturated fat and cholesterol. While we do need a certain amount of fat in the diet there is no nutritional requirement for saturated fat. Cow’s milk is high in the unhealthy saturated fats and low in the healthy polyunsaturated essential fatty acids, which are required in the diet for good health. Most people eat much more fat than they need, and making minor changes to the diet (cutting down on fat) can make a big difference over time.

A number of small-scale studies (of less than 35 obese adults) have suggested that the consumption of dairy products may actually help people lose weight (Zemel et al., 2004; Zemel et al., 2005). In these studies Professor Zemel, who has received a considerable amount of funding from the National Dairy Council (COS, 2005), suggests that diets containing calcium from dairy foods might affect fat cell metabolism in such a way that greater weight loss can occur despite an identical calorie intake with a control group not consuming so much dairy. Interestingly, a subsequent study (by a research group including Zemel but not as the first named author) found no evidence that a diet high in dairy products enhances weight loss (Thompson et al., 2005).

Dr Amy Joy Lanou, the nutrition director of the PCRM, warns that care should be taken when interpreting the findings from Zemel’s trials. Furthermore, Lanou suggested that the US National Dairy Council’s claims promoting dairy consumption for weight loss went well beyond Zemel’s findings. Lanou suggests that it was likely that calorie restriction, not dairy consumption, caused the weight loss reported in these studies (Lanou, 2005).

In June 2005 the PCRM decided enough was enough and filed two separate lawsuits to stop the multimillion-dollar advertising campaign claiming that milk facilitates weight loss. The PCRM filed one lawsuit to the US Food and Drugs Administration and the other to the US Federal Trade Commission. In the lawsuit the PCRM charged the National Dairy Council, the International Dairy Foods Association, Dairy Management Incorporated, Dannon Company, Kraft Foods and other dairy manufacturers with purposefully misleading customers (PCRM, 2005).

Despite the dairy industry’s claims, scientific studies show that adding dairy products to the diet does not help control weight; in fact the research confirms that in many cases the reverse is true, consuming milk and dairy foods can lead to weight gain. Some studies designed to test the effects of dairy consumption on weight found no difference in weight between groups consuming relatively large amounts of dairy foods compared to groups consuming little (Lappe et al., 2004; Gunther et al., 2005). Another study, this time of the effects of just calcium supplementation on weight loss in women who had recently given birth, found no relationship between calcium supplementation and weight loss (Wosje, 2004). Researchers at the University of British Columbia in Vancouver, Canada, who reviewed the scientific literature on the effects of dairy products or calcium supplements on body weight found that out of nine studies on dairy products, seven showed no significant difference while two studies linked weight gain to dairy consumption (Barr et al., 2003). Furthermore, out of 17 studies on calcium supplementation, just one reported weight loss.

A recent large scale study that followed over 12,000 children for three years concluded that the children who drank the most milk gained the most weight (Berkey et al., 2005). The analyses showed that out of milk, calcium, dairy fat and total energy intake, it was energy intake that was the most important predictor of weight gain. The authors attribute this weight to… you’ve guessed it, the added calories! To most people it is just common sense, a calorie is a calorie and weight gain or weight loss is a case of mathematics. If you take in more energy (calories) than you use, you will gain weight. If you use up more energy than you consume, you will lose weight. There is no magic bullet, and if there were it seems very unlikely that it would be cow’s milk.

Osteoporosis

Bones consist of a thick outer shell and a strong inner mesh filled with a protein called collagen, calcium salts and other minerals. Osteoporosis (meaning porous bones) occurs when calcium is lost from the bones and they become more fragile and prone to fracture. This debilitating condition tends to occur mostly in postmenopausal women due to a lack of the hormone oestrogen, which helps to regulate the incorporation of calcium into the bones. Osteoporosis tends to occur mostly among postmenopausal women aged between 51 and 75. It can occur earlier or later and not all women are at equal risk of developing osteoporosis.

Osteoporosis is sometimes called the silent disease as there are often no symptoms until a fracture occurs. Although the whole skeleton is usually affected, fractures mostly occur in the wrist, spine and hip. One in two women and one in five men in the UK will suffer a fracture after the age of 50; in fact every three minutes someone has a fracture due to osteoporosis (National Osteoporosis Society, 2005). However, osteoporosis has been diagnosed in people as young as 20. The dairy industry has responded to this health scare by promoting the consumption of milk, cheese and yogurt directly to teenage girls in a campaign run by the Milk Development Council (MDC, 2005a).

It is deeply entrenched in the British psyche that calcium from dairy sources is essential for good bone health. However, a recent review on dairy products and bone health published in the official journal of the American Academy of Pediatrics challenged this misleading notion by concluding that there is very little evidence to support increasing the consumption of dairy products in children and young adults in order to promote bone health (Lanou et al., 2005). This review examined the effects of dairy products and total dietary calcium on bone integrity in children and young adults and found that out of 37 studies, 27 showed no relationship between dairy or dietary calcium intake and measures of bone health. In the remaining studies the effects on bone health were either small or results were confounded by the fortification of milk with vitamin D.

American women are among the biggest consumers of calcium in the world, yet they have one of the highest levels of osteoporosis (Frassetto et al., 2000). African Bantu women, on the other hand, eat almost no dairy products at all; they have a relatively low calcium intake, mainly from vegetable sources, and typically have up to 10 children each. Yet osteoporosis is virtually unknown among Bantu women (Walker et al., 1972).

It seems that the more dairy produce we consume, the higher our risk of fracture. The Harvard Nurses Health study examined whether higher intakes of milk can reduce the risk of osteoporotic fractures. The study observed over 75,000 women for 12 years and concluded that increasing milk consumption did not confer a protective effect against hip or forearm fracture (Feskanich et al., 1997). In fact the report suggested that an increased calcium intake from dairy foods was associated with a higher risk of fracture.  

It has been suggested that calcium loss from the bone is promoted by a high intake of animal protein. One study of 1,600 older women examined the level of bone loss and found vegetarians had only 18 per cent less bone mineral compared to omnivores who had lost 35 per cent bone mineral by the age of 80 (Marshet al., 1988). Another study of 1,035 elderly women found that women with a high ratio of animal to vegetable protein intake had a greater risk of hip fracture than those with a low ratio (Sellmeyer et al., 2001). In a similar study that analysed the incidence of hip fracture in relation to the consumption of animal and vegetable protein in 33 countries, it was concluded that moderating the consumption of animal food might protect against hip fracture (Frassetto et al., 2000). Cross-cultural studies summarising data on protein intake and fracture rates from 16 countries compared industrialised and non-industrialised lifestyles and revealed strong links between a high animal protein diet, bone degeneration and the occurrence of hip fractures (Abelow et al., 1992). In the book The China Study, Campbell observed that in rural communities where animal protein made up just 10 per cent of the total protein intake (the other 90 per cent coming from plant-based sources) the bone fracture rate was one-fifth of that in the US where 50 per cent or more of total protein is made up of animal protein (Campbell and Campbell, 2005), again indicating a link between animal protein and bone degeneration.

But what is the mechanism for this process? As food is digested acids are released into the blood, and the body attempts to neutralise the acid by drawing calcium from the bones. This calcium is then excreted in the urine (the calciuric response). Animal protein from cow’s milk and dairy products as well as meat, fish and eggs has a particularly bad effect because of the greater amount of sulphur-containing amino acids it contains compared to plant protein. As the sulphur content of the diet increases so does the level of calcium in the urine. Studies reveal that an animal protein diet (with the same total quantity of protein as a vegetarian diet) confers an increased risk for uric acid stones (Breslau et al., 1988). Furthermore the animal-protein induced calciuric response may be a risk factor for the development of osteoporosis. The traditional Inuit (or Eskimo) diet is made up almost entirely of animal protein. Inuits potentially have one of the highest calcium intakes in the world (up to 2,500 milligrams per day) depending on whether they eat whole fish, including the bones, or not. They also have a high rate of osteoporosis, even higher than white Americans (Mazess et al., 1974; Mazess et al., 1975; Pratt et al., 2001).

There are many factors linked to bone health that may even be more important than calcium. For example, when the bone density of 80 young women was monitored over a 10-year period, it showed that exercise was more important than calcium intake (Lloyd et al., 2004). In older people, a 15-year investigation into whether low calcium intake was a risk factor for hip fractures concluded that cutting back on dairy did not increase the risk and that physical activity provided better protection (Wickham et al., 1989). The discovery of 18th-century human bones under a London church revealed that today’s women lose far more calcium than our ancestors (Lees et al., 1993). This may be attributed to a lower degree of physical activity. This research supports an increasing amount of evidence that physical activity is a key factor in reducing osteoporosis risk. 

An increasing amount of evidence now shows that milk is not the best source of calcium at all and suggests that our bone health would benefit enormously if we switched to plant-based sources. Interestingly, a large share of the calcium in our diets (over 50 per cent) comes from sources other than dairy foods (FSA, 2003b). This is not surprising as most people in the world (over 70 per cent) obtain their calcium from plant-based sources rather than dairy products. Good plant-based sources of calcium include non-oxalate (eg spinach) dark green leafy vegetables such as broccoli, kale, spring greens, cabbage, bok choy and watercress. Also rich in calcium are dried fruits, such as figs and dates, nuts, particularly almonds and brazil nuts, and seeds including sesame seeds and tahini (sesame seed paste) which contains a massive 680mg of calcium per 100g. Pulses including soya beans, kidney beans, chick peas, baked beans, broad beans, lentils, peas and calcium-set tofu (soya bean curd) provide a good source of calcium. A good additional source is calcium-enriched soya milk. Interestingly, the calcium in dairy products is not as well absorbed as that in many dark green leafy vegetables, for example, in one study calcium absorbability from kale was demonstrated to be considerably higher than that from cow’s milk (Heaney and Weaver, 1990).

In summary, research suggests that physical (especially weight-bearing) exercise is the most critical factor for maintaining healthy bones, followed by improving the diet and lifestyle; this means eating plenty of fresh fruit and vegetables, and cutting down on caffeine and avoiding alcohol and smoking.